Note on flat join the pattern mentions: priscillascrochet.net/freepatterns.html and scroll down to find the title to download pdf

Here is how I made my handles:

After doing the granny square patchwork I used 3 rounds of brown (worsted weight doubled) to finish off before adding handels. Using K hook & 2 strands of yarn:

row 1. Attach to side of bag in v corner, Chain 3, Double Crochet this row by making 1 DC in each ch 3 space from each granny square. When you get to one of the 4 peaks in the granny squares do (1 DC, ch1, 1DC, ch1, 1DC) in the same ch3 space on that granny square then continue with 1DC in each ch 3 space of the other granny squares. For the V’s or dips in the bag (front, back and the opposite side you attached the yarn) do 2 DC decreases over the 4 spaces that make the V or dip. After you complete this row, slip stitch into the top of your ch3 that you made at the beginning of this row, ch1 and sc in the same space (do not turn)

row 2. single crochet each stitch of this row. when you come to the top on one of the 4 peaks (your middle double crochet in your row 1 peak grouping) do: (sc, ch2, sc - for a larger hole do a ch.3 or ch.4) in the same stitch at your peaks this will leave a space for you to attach your material strapping. then continue your sc in each stitch around. When you finish row slip stitch into your 1st sc made (do not turn or chain)

row 3. this row is a surface crochet row to give more durability. surface crochet each stitch around and the V or dip spaces…to work the top of each 4 peaks surface crochet till you get to the hole space you made in row 2, slip stitch in hole space and ch.1 then surface crochet again till your done with round.

Straps: take material and with a large hook put through row 2 holes made at the top of each peak and make knot.